摘要
火山喷发物记录了岩浆的整个活动历史,对火山喷发物的研究可以了解大量的岩浆活动特征信息。本文对腾冲火山区的三座全新世火山——黑空山、马鞍山和打莺山火山熔岩进行了详细的研究,包括熔岩和斑晶的成分、显微结构特征和斑晶的晶体大小分布(CSD)分析。研究发现,黑空山、马鞍山和打莺山火山熔岩以粗安岩为主,三座火山粗安岩中的斑晶成分范围接近,但它们的显微结构特征具有一定的差异,反映了不同的岩浆环境,推测来自不同的岩浆囊。黑空山粗安岩中斜长石斑晶的CSD曲线呈微上凹形,反映了小规模的岩浆混合作用。马鞍山和打莺山粗安岩的微斑晶CSD曲线呈很好的线性关系,说明微斑晶形成时的环境相对稳定,推测这些微斑晶是在岩浆上升过程中,停留在地壳的某处并形成一个小型的岩浆囊后受围岩的冷却作用形成。根据以上的分析,认为腾冲火山区下在横向和纵向上均至少存在两个岩浆囊。
The products of volcanic eruption record the whole activity history of magma,and hence they may provide abundant information about the magmatic activity characteristics,In this paper,the lavas of three Holocene volcanoes in Tengchong volcanic field,Heikongshan volcano,Ma＇anshan volcano and Dayingshan volcano,were studied in detail,including the compositions of bulk rocks and phenocrysts,texture features and crystal size distribution（CSD） of phenocrysts,The study shows that the lavas in Heikongshan,Ma＇anshan and Dayingshan volcanoes are mainly trachyandesite,and the compositions of phenocrysts in trachyandesite are similar,The textures of the trachyandesite in these three volcanoes,however,are different obviously,which reflects different magma environments,so we speculate that they are from different magma chamber,The CSD curves of plagioclase phenocrysts in Heikongshan trachyandesite lavas show slightly concave,which reflect a small scale of magma mixing,The CSD curves of plagioclase micro-phenocrysts in Ma＇anshan and Dayingshan lavas are good linear,indicating the formation environment of micro-phenocrysts is relatively stable,We speculate that these micro-phenocrysts were formed because of the cooling of the surrounding rocks,after the magma rising and then remaining in the crust and forming a small magma chamber,The analysis aforementioned shows that there are at least two magma chambers in the horizontal and vertical directions respectively under Tengchong volcanic field.
出处
《岩石学报》
SCIE
EI
CAS
CSCD
北大核心
2012年第4期1205-1216,共12页
Acta Petrologica Sinica
基金
地震行业专项(200708-27)
国家自然科学基金项目(40972209)联合资助
关键词
粗安岩
显微结构
晶体大小分布
黑空山火山
马鞍山火山
打莺山火山
Trachyandesite
Texture
Crystal size distribution
Heikongshan volcano
Ma＇anshan volcano
Dayingshan volcano
